If you are developing using Windows 2003 Server and running the NTFS
file system setting proper permissions on the database folder in your
website is done like so.

Using "my computer" browse to the folder in your web that you need to set
permissions on.

Right click on that folder and then choose the "security" tab.

Give the "Internet Guest Account" Modify Permissions(depending on what you are doing you can sometimes get
away with less permissions)
This will check all the boxes under modify as well.

In some cases you may want to go into the advanced tab and check both
checkboxes shown in order to make sure the permissions you need get set. It
really all depends on the situation.

BTW:

It is referred to as the internet guest
account but that isn't the actual username. The username is different for
every machine. It usually starts off with "IUSR_" and then your machine
name. "Internet Guest Account" is always the account's full name as labeled
by IIS when it is installed.

Regardless,

If an account isn't listed you have to add it.

Click (add-advanced-find now) and it will list off all the user accounts on
the machine

You can also click (add-advanced) and simply
type in the account name or part of it.

Some more tips:

If on a local machine you always just give the "everyone" account full
control which is pretty much going to make anything work.

To see all the user names and groups on the system you can also go to computer management in your server's administrative tools
and view all of the accounts and groups there under "Local Users and Groups

Now, if you are using ASP.NET you need to
give permissions to an account called ASPNET. It wont show up in the user
list. You'll need to click "add" and then type in "ASPNET"

Regarding hosting companies..

Now.. obviously if you are hosting on someone else's server you may not be
able to set permissions like this.

Ultimately, if you are hosting somewhere and ASP and Database
connectivity is part of your hosting plan. It is the hosting company's
responsibility to set these permissions for you when asked or to give you a
special interface to do so on your own. If they are not helping you do this
then maybe it is time to get a hosting company that is serious about your
ASP Hosting Needs.

Also... JUST TO BE PERFECTLY CLEAR

The permissions we are talking about cannot be set via FTP or FrontPage
access to your web site.
These permissions usually must be set like shown above or via a special
interface meant to set the permissions correctly. For all you people out
there messing with the permissions you see in FTP and FrontPage.. you are
wasting your time and possibly creating problems in your web.